Games that you download through PlayStation plus requires it and if you don't have PlayStation plus you won't be able to play it. Its similar to Xbox live. Hope this helps.
That is correct, I know, sony has weird policies but that's how it works with them. Now if you purchase a game while being on the trial I believe you should still be able to play it but if its free or something like that once the trials over you won't be able to play it until you subscribe to PlayStation plus again.